1. Field of the Invention
This invention generally relates to a safety net arrangement for protecting workers and passersby from injury during construction of multi-floor buildings and, more particularly, to manually moving a deployed net, and optionally a curtain, by a worker located at a safe protected position in which the net shields the worker from injury.
2. Description of Related Art
It was known from my U.S. Pat. No. 3,949,834 to erect safety nets adjacent an outer face of a building under construction in order to catch workers and/or objects falling off a floor above the net, thereby protecting the fallen worker, workers on lower floors, as well as passersby at ground level, from being injured. The outer edge of each net was supported at an outer end of a cantilevered support pole whose inner end was connected to a floor bracket bolted to a lower floor. The inner edge of each net was bolted to the nearest higher floor by eye-bolts or by cables tied to the nearest perimeter columns.
Despite its use in many buildings under construction, the arrangement of the '834 patent was not easily movable from lower to higher floors as construction proceeded, since the net supports had to be unbolted and untied from lower floors prior to being moved, rebolted and retied on higher floors. Since the disassembled net exposed workers and passersby to potential injury from falling workers and/or objects, extra redundant nets were erected while other safety nets were being moved--a procedure which was both labor-intensive and costly.
It was also known from my U.S. Pat. No. 4,856,615 to attach elongated tracks or guide rails to a building adjacent an outer face thereof. Net support structures for suspending a safety net in a deployed condition were mounted on the guide rails for vertical movement therealong while constantly maintaining the net deployed. Manually-operated overhead winches were mounted on the guide rails above the net support structures and were connected to the latter by depending hoisting cables. To move the net support structures and, in turn, the net, a worker had to climb up to a higher floor to reach the overhead winch, thereby exposing himself or herself to the risk of injury from falling objects from above.
It was also known from my U.S. Pat. No. 4,838,382 to raise a deployed safety net without using guide rails attached to the building. Again, manually-operated overhead winches were mounted above, and connected by depending hoisting cables to, the net support structures. Again, a worker had to operate the winch from an exposed, unprotected position, thereby risking injury from falling objects from above.
The art has also proposed raising safety nets by power-assisted means. For example, U.S. Pat. No. 4,732,234 described the assistance of a power crane, and U.S. Pat. No. 4,892,169 described the assistance of hydraulic pumps and motors.
It was also known in the art to stretch curtains between, and fasten the curtains to, spaced-apart building columns or masts. For example, the curtain may be a tarpaulin to act as a weather shield, to keep heat in the building, or as a screen to keep spray paint or spray fire-proofing materials in the building. The curtain may be a safety barrier flush against the building face to prevent workers from falling off an unfinished floor, or may be an advertising banner, etc. Such curtains were held in place by cables tied around the nearest perimeter columns and were not easily movable from one floor to the next as building construction proceeded. Indeed, the cables were typically untied, the curtains folded and thereupon unfolded before being attached to the columns on another floor. This was a laborious, time-consuming procedure.
The known safety nets were also supported entirely by rigid supports. Although generally satisfactory for securely holding the nets in place and for catching objects and workers, experience has shown, particularly in the case of a fallen worker, that injury might result to a fallen worker because of the rather "hard" landing in the net due, in large part, to the rigid support structures holding the net. The rigid support structures do not readily allow the net to collapse around the fallen worker to prevent him or her from rebounding off the net.